Infective endocarditis

Question 1

What is the definition of infective endocarditis?

Answer 1

Endovascular infection of the cardiac structures including cardiac vales, atrial and ventricular endocardium and intracardiac foreign bodies e.g. prosthetic valves, pacemaker leads etc.

Question 2

How common is infective endocarditis?

Answer 2

Annual UK incidence is 6-7/100,000 but more common in developing countries. ↑↑ mortality and morbidity rate. Aortic and mitral valves most commonly involved

Question 3

What is the pathophysiology of infective endocarditis?

Answer 3

• 2 main factors contribute to acquiring endocarditis: organisms in the bloodstream and abnormal cardiac endothelium
• Damaged endocardium = platelet and fibrin deposition to which organisms adhere and grow → infective vegetation
• α-haemolytic viridans streptococci – most common from mouth
• Staph aureus – IVDU
• Modified Duke criteria used to diagnose endocarditis

Question 4

What is the aetiology/risk factors of infective endocarditis?

Answer 4

• Poor dental hygiene/dental treatment
• IV drug user – right sided lesion more common
• IV cannula
• Soft tissue infections
• Cardiac surgery
• Pacemaker
• Prior antibiotic therapy – culture negative endocarditis

Question 5

What are the signs/symptoms of endocarditis?

Answer 5

• Fever
• Malaise
• Janeaway lesions
• Splinter haemorrhages
• Conjunctival haemorrhages
• Clubbing
• Oslers nodes – palmar side of hand
• Petechiae
• Roth spots (eyes)
• Cardiac murmur
• Cardiac failure – ventricular arrhythmias/conduction disturbances
• Splenomegaly
• Haematuria

Question 6

What diseases present similarly to infective endocarditis?

Answer 6

• SLE
• Cardiac tumour
• Lyme disease
• Antiphospolipid syndrome

Question 7

What investigations are carried out for suspected infective endocarditis?

Answer 7

• Blood culture, microscopy and specificity – 3 sets from different venepuncture sites
• Serological test for Q fever – IgG antibodies
• FBC - ↓ Hb, ↑ WCC
• U&Es - ↑ urea and creatinine
• LFTs - ↑ serum alkaline phosphatase
• ESR/CRP - ↑
• Urinalysis – protein and blood present
• CXR – pulmonary oedema in left side and pulmonary emboli/abscess in right side
• Echocardiography – shows mass on the valve, implanted material or abscess

Question 8

What are the surgical treatments for infective endocarditis?

Answer 8

valve replacement surgery - if the valve is destroyed

Question 9

What are the pharmacological treatments for infective endocarditis?

Answer 9

• Prolonged antibiotics (normally 4-6 weeks) – almost always involves penicillin so beware of allergy